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9966 [12]
3 years ago
6

You have 2000 grams of substance A which has decay constant 0.03, and you have 3000 grams of substance B, which has decay consta

nt 0.05. After how many years will the amounts of the two substances be equal?
Mathematics
1 answer:
joja [24]3 years ago
6 0

Answer:

If you have a quantity X of a substance, with a decay constant r, then the equation that tells you the amount of substance that you have, at a time t, is:

C(t) = X*e^(-r*t)

Now, we know that:

We have 2000g of substance A, and it has a decay constant of 0.03 (i assume that is in 1/year because the question asks in years)

And we have 3000 grams of substance B, with a decay constant of 0.05.

Then the equations for both of them will be:

Ca = 2000g*e^(-0.03*t)

Cb = 3000g*e^(-0.05*t)

Where t is in years.

We want to find the value of t such that Ca = Cb.

So we need to solve:

2000g*e^(-0.03*t) = 3000g*e^(-0.05*t)

e^(-0.03*t) = (3/2)e^(-0.05*t)

e^(-0.03*t)/e^(-0.05*t) = 3/2

e^(t*(0.05 - 0.03))  = 3/2

e^(t*0.02) = 3/2

Now we can apply Ln(x) to both sides, and get:

Ln(e^(t*0.02)) = Ln(3/2)

t*0.02 = Ln(3/2)

t = Ln(3/2)/0.02 = 20.3

Then after 20.3 years, both substances will have the same mass.

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ANY number that you can completely write down on paper with digits...
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2 years ago
The midpoint of AB = ([?],[ ])
3241004551 [841]

Answer:

(0,0)

Step-by-step explanation:

x_{m}=\frac{-2+2}{2}=0\\y_{m}=\frac{-2+2}{2}=0\\

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3 years ago
Which system of inequalities is represented by the graph?
timofeeve [1]

Answer:

The system of inequalities " x + 2 y ≤ 5 and 3 x + y ≤ 4 " is represented by the graph ⇒ D

Step-by-step explanation:

To find the answer let us find the equation of each line

Blue line:

∵ The line passes through points (5 , 0) and (0 , 2.5)

- Find the slope of the line

∵ m = Δy/Δx

∴ \frac{0-2.5}{5-0}=\frac{-2.5}{5}

∴ m = -0.5

- The form of the equation is y = m x  + b, where b is the

   y-intercept (value y at x = 0)

∵ y = 2.5 at x = 0

∴ b = 2.5

- Write the equation of the line

∴ y = - 0.5 x + 2.5

- Multiply both sides by 2

∴ The equation of the blue line is 2 y = - x + 5

- The shading is under the line and the line is solid, that means

  2 y is less than or equal - x + 5

∴ The inequality of the blue line is 2 y ≤ - x + 5

Red line:

∵ The line passes through points (3 , -5) and (0 , 4)

- Find the slope of the line

∴ m=\frac{-5-4}{3-0}=\frac{-9}{3}

∴ m = -3

∵ y = 4 at x = 0

∴ b = 4

- Write the equation of the line

∴ y =  -3 x + 4

∴ The equation of the red line is y = -3 x + 4

- The shading is below the line and the line is solid, that means

  y is less than or equal -3 x + 4

∴ The inequality of the red line is y ≤ -3 x + 4

Let us find which answer is the same with this system of inequalities

∵ 2 y ≤ - x + 5

- Add x to both sides

∴ x + 2 y ≤ 5 ⇒ same as the first inequality of answer D

∵ y ≤ -3 x + 4

- Add 3 x to both sides

∴ 3 x + y ≤ 4 ⇒ same as the second inequality of answer D

The system of inequalities " x + 2 y ≤ 5 and 3 x + y ≤ 4" is represented by the graph

4 0
3 years ago
How can i get my answer for 5+(-34)
julia-pushkina [17]

Hello there.

Answer: ⇒⇒⇒⇒-29

Step-by-step explanation:

Remove parenthesis.

5-34

Subtract the numbers.

5-34=-29

Hope this helps!

Thank you for posting your question at here on brainly.

-Charlie

4 0
2 years ago
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